Structure-activity relationships for the glutathione conjugation of 2-substituted 1-chloro-4-nitrobenzenes by rat glutathione S-transferase 4-4
| Autor: | Nico P. E. Vermeulen, M.J. de Groot, H. Van Der Goot, E. M. Van Der Aar, G. J. Bijloo |
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| Přispěvatelé: | Medicinal chemistry, Molecular and Computational Toxicology |
| Jazyk: | angličtina |
| Rok vydání: | 1996 |
| Předmět: |
Steric effects
Chemistry Stereochemistry Substituent General Medicine Glutathione Toxicology Kinetic energy Transition state Rats chemistry.chemical_compound Structure-Activity Relationship Reaction rate constant Nucleophile SDG 3 - Good Health and Well-being Physical chemistry Animals Kappa Nitrobenzenes Software Glutathione Transferase Protein Binding |
| Zdroj: | van der Aar, E M, de Groot, M J, Bijloo, G J, van der Goot, H & Vermeulen, N P E 1996, ' Structure-activity relationships for the glutathione conjugation of 2-substituted 1-chloro-4-nitrobenzenes by rat glutathione S-transferase 4-4. ', Chemical Research in Toxicology, vol. 9, pp. 527-534 . https://doi.org/10.1021/tx9501391 Chemical Research in Toxicology, 9, 527-534. American Chemical Society |
| ISSN: | 0893-228X |
| DOI: | 10.1021/tx9501391 |
| Popis: | In the present study structure--activity relationships (SAR's) are described for the experimentally determined kinetic parameters (Km, kappa cat, and kappa cat/Km) of the GST 4-4-catalyzed reaction between GSH and 10 2-substituted 1-chloro-4-nitrobenzenes. Steric, lipophilic, and electronic parameters were correlated with the kinetic parameters. Moreover, charge distributions and several energy values were calculated for the substrates and the corresponding Meisenheimer intermediates with MeS- as a model nucleophile for the thiolate anion of GSH and used in the regression analyses. The correlations obtained were compared with the corresponding SAR's for the base-catalyzed GSH conjugation reaction at pH 9.2. A high correlation coefficient was found between the kinetic parameter kappa s for the base-catalyzed reaction and the Hammett substituent constant (sigma p). Much lower correlation coefficients were obtained with kappa cat and sigma p and with kappa cat/Km and sigma p. Moreover, the reaction constant rho was significantly higher for the base-catalyzed than for the enzyme-catalyzed reaction. Also, high correlations were found between the kinetic parameters and the charges on the p-nitro substituent in the substrates. When kappa s was plotted against these charges, a linear relationship was found in which the slope was larger than the slope of a corresponding plot with kappa cat/Km. The Hammett sigma p can be divided into an inductive (F) and a resonance (R) component. With multiple regression between the kinetic parameters and F and R, higher correlation coefficients were obtained than with sigma p alone. Our observations suggest that the transition states for the base-catalyzed and the GST 4-4-catalyzed GSH conjugation reaction are different. Moreover, single classical physiochemical and computer-calculated molecular parameters and combinations of them can be an alternative approach for examining SAR's for spontaneous and GST-catalyzed GSH conjugation reactions. |
| Databáze: | OpenAIRE |
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